Design and Verification of a Low-Power GPS-Disciplined Oscillator For Use In Distributed Sensor Arrays

Open Access
Author:
Boehmer, Tyler J
Graduate Program:
Electrical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
June 14, 2013
Committee Members:
  • Sven G Bilen, Thesis Advisor
Keywords:
  • GPS
  • disciplined
  • oscillator
  • global
  • positioning
  • system
  • clock
  • low
  • power
  • distributed
  • sensor
  • array
  • network
  • reflectometry
Abstract:
The geoPebble system being developed at The Pennsylvania State University is a distributed wireless sensor network that requires high timing accuracy with low power consumption. Although chip-scale atomic clocks have advanced significantly, cost continues to be prohibitive. GPS signals are commonly used to discipline ovenized oscillators in order for the local oscillator to inherit the long term stability of GPS timing; however, commercially available GPS-disciplined oscillators (GPSDOs) use ovenized oscillators and take an extended period of time to reach their stated accuracy, resulting in a large power consumption of over a watt. This has limited their adoption in low-power applications, as well as low-cost applications. Modern temperature-compensated crystal oscillators have advanced to a stability that enables the possibility of duty cycling a GPS receiver and intermittently correcting the oscillator for drift. A GPSDO is presented that achieves an accuracy of 5~$\mu$s~RMS in its operational environment, while consuming only 45~mW of average power.